900 research outputs found
Quantum nature of the critical points of substances
Thermodynamics of chemical elements, based on the two-component
electron-nuclear plasma model shows that the critical parameters for the
liquid-vapor transition are the quantum values for which the classical limit is
absent.Comment: 4 pages, no figure
True Dielectric and Ideal Conductor in Theory of the Dielectric Function for Coulomb System
On the basis of the exact relations the general formula for the static
dielectric permittivity e(q,0) for Coulomb system is found in the region of
small wave vectors q. The obtained formuladescribes the dielectric function
e(q,0) of the Coulomb system in both states in the "metallic" state and in the
"dielectric" one. The parameter which determines possible states of the Coulomb
system - from the "true" dielectric till the "ideal" conductor is found. The
exact relation for the pair correlation function for two-component system of
electrons and nuclei g_ei(r) is found for the arbitrary thermodynamic
parameters.Comment: 5 pages, no figure
Angular Schmidt Modes in Spontaneous Parametric Down-Conversion
We report a proof-of-principle experiment demonstrating that appropriately
chosen set of Hermite-Gaussian modes constitutes a Schmidt decomposition for
transverse momentum states of biphotons generated in the process of spontaneous
parametric down conversion. We experimentally realize projective measurements
in Schmidt basis and observe correlations between appropriate pairs of modes.
We perform tomographical state reconstruction in the Schmidt basis, by direct
measurement of single-photon density matrix eigenvalues.Comment: 5 pages, 4 figure
Point-contact study of the LuNi2B2C borocarbide superconducting film
We present point-contact (PC) Andreev-reflection measurements of a
superconducting epitaxial c-axis oriented nickel borocarbide film LuNi2B2C
(Tc=15.9 K). The averaged value of the superconducting gap is found to be 2.6
+/-0.2 meV in the one-gap approach, whereas the two-gap approach results in
2.14+/-0.36 meV and 3.0+/-0.27 meV. The better fit of the Andreev-reflection
spectra for the LuNi2B2C - Cu PC obtained by the two-gap approach provides
evidence for multiband superconductivity in LuNi2B2C. For the first time, PC
electron-phonon interaction (EPI) spectra have been measured for this compound.
They demonstrate pronounced phonon maximum at 8.5+/-0.4meV and a second shallow
one at 15.8+/-0.6 meV. The electron-phonon coupling constant estimated from the
PC EPI spectra turned out to be small (~ 0.1), like in other superconducting
rare-earth nickel borocarbides. Possible reasons for this are discussed.Comment: 5 pages, 5 figures, V2: figs. 2 & 5 captions are corrected, and new
Refs. 4, 6, 12, 13, 14 are adde
Identity of electrons and ionization equilibrium
It is perhaps appropriate that, in a year marking the 90th anniversary of
Meghnad Saha seminal paper (1920), new developments should call fresh attention
to the problem of ionization equilibrium in gases. Ionization equilibrium is
considered in the simplest "physical" model for an electronic subsystem of
matter in a rarefied state, consisting of one localized electronic state in
each nucleus and delocalized electronic states considered as free ones. It is
shown that, despite the qualitative agreement, there is a significant
quantitative difference from the results of applying the Saha formula to the
degree of ionization. This is caused by the fact that the Saha formula
corresponds to the "chemical" model of matter.Comment: 9 pages, 2 figure
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